The present invention relates to a spooling device for hydraulic cylinder and a method for assembling same.
In the operation of hydraulic cylinders a desirable feature is the ability to know the specific position of the cylinder during its extension and retraction. With many implements the hydraulic cylinder is not visible, and therefore electronic means have been provided for sensing the relative position of the hydraulic cylinder and its extension and retraction.
Electrical sensors have included a wiper on the piston rod that wipes along an elongated probe during the movement of the piston. By connecting an electrical circuit through the wiper and the probe it is possible to determine the specific position of the piston within the cylinder.
Connection of sensor electronic circuitry outside the cylinder is usually done by a wire which extends from the sensor within the cylinder to an external connection which can be connected to circuitry outside the cylinder.
The wire is connected at one end to a header assembly threaded within the walls of the cylinder and at the other end to the sensing apparatus within the cylinder.
The length of wire required to extend from the sensing device to the header assembly varies depending upon the diameter of the cylinder. It is therefore necessary to have wires of differing lengths to fit cylinders of different diameters.
Another problem encountered is the connection of the wire to the header that is threaded within the cylinder. As the header is rotated during threading, the wire is also rotated. A desirable feature would be the ability to keep the wire stationary while threading the header assembly into the wall of the cylinder.
Therefore a primary object of the present invention is the provision of an improved spooling device for hydraulic cylinder and method of assembling same.
A further object of the present invention is the provision of a header assembly used in the hydraulic cylinder which permits the wire to remain stationary while the header assembly is rotatably threaded into a threaded opening in the wall of the cylinder.
Another object of the present invention is the provision of an improved spooling device for hydraulic cylinder which can be used to wind up excess length in the wire that extends from the header assembly to the position sensor within the cylinder.
A further object of the present invention is the provision of an improved spooling hydraulic cylinder wherein the same length of wire can be used in the manufacturer of numerous cylinders having various diameters.
Another object of the present invention is the provision of an improved spooling device for hydraulic cylinder and method for assembly of same which is economical to manufacture, durable in use and efficient in operation.
The foregoing objects may be achieved by a hydraulic cylinder assembly comprising an elongated cylinder having a cylinder wall, first and second ends and a longitudinal bore extending therethrough. The cylinder includes a first hydraulic port at one end of the cylinder and a second hydraulic port at the other end. A piston is mounted for reciprocating longitudinal movement within the bore of the cylinder. A piston rod includes a first end attached to the piston and a second end extending outside the second end of the cylinder. The rod is movable during reciprocation of the piston within the bore of the cylinder from a retracted position to an extended position.
A header assembly is mounted to the cylinder wall adjacent the first end of the cylinder. An electrical assembly engages one of the pistons and the piston rod for sensing the relative position of the piston rod as it moves between its retracted and extended positions. The electrical sensor assembly includes a spool with an outer cylindrical surface spaced radially inwardly from the header assembly. A wire includes a first end connected to the header assembly and a second end connected to the sensor assembly. The spool is capable of rotation to a final position to wind any slack portion of the wire around the outer cylindrical surface of the spool. A mechanism engages the spool to hold the spool against rotation after it has been moved to its final position.
According to one feature of the invention the cylindrical header assembly includes a first header member and a second header member that are capable of rotating with respect to one another so that the second header member will stay stationary during rotation of the first header to thread the first header into the threaded opening in the wall of the cylinder. The wire is attached to the second header member whereby the wire will not rotate during rotation of the first header member to thread the first header member into the threaded opening.
The method of the present invention comprises attaching a header assembly to the cylindrical wall of the hydraulic cylinder. A first end of a wire is attached to the header assembly and a second end of the wire is attached to the spool and then the slack in the wire is would around the spool surface. The spool is held stationary against movement away from a final position after winding of the slack in the wire around the spool surface.